Method of coating metal



Patented Apr. 28, 1936 A PATENT oFFl'cEj 2,038,549 Muri-ion oF ooA'riNG METAL .Elgin Carleton Domm, Niles,

rNational-Standard Company,

corporation of Michigan Mich., assignor to Niles, Mich., a

Original application January 25, 1933, Serial No. 653,549. Divideda'nd this application September 8, 1934, Serial No. 743,282

s claims, (cm1-7o) This invention relates to limprovements in` method of coating metal.

In the Crapo Patent No. 1,984,335, issued Dec. 11, 1934, is described a method of coating a ferrous article by hot-galvanizing it with zinc, and over that depositing by some other method an additional coating of zinc or a coating of cad-- mium.

It has now been discovered that a corrosionresisting coating ofA cadmium may be produced which .is considerably more resistant to corrosion, particularly to the type of which the salt spray is typical.

At the same time a relatively thin coating may be produced` for equivalent protection to such corrosion, and such coating may be correspondinglyv more exactly controlled -as to depth and thickness, by the present method.

- of cadmium is then put over the first coat by elecv The invention is particularly applicable to coating strands of wire to beused in reinforcing the bead of a tire. The-wire when so used commonly acts as a tension-member, and is imbedded in a rubber or rubber compound. When so used, the wire is' exposed to corrosive and rusting agents, particularly to moisture which may seep into the tire.

Thedrawing shows in diagrammatic form an embodiment of my invention.A 1, I

In accordance with the invention, a metal, for example wire suitable for use in tire beads, is first hot-dipped to provide a coating of cadmium. This may be done, for example, by dipping the wire in hot. molten cadmium. Another coating troiysis or electroplating.

Not only does a double coating applied by the above-mentioned method give very good corrosion resistancabut it has been discovered that the electro-coat tends to illl in the depressions, in the lower cadmium coat and thus produce a uniform and smooth coating. This is wholly unexpected.

If desired, copper or other suitable. material may be applied over the corrosive-resistant coating in order to increase the adhesiveness of the wire to rubber. It is frequently desirable to apply such a, coating when wire is used as a reinforcement for a tire bead. l

The new process herein described is especially useful in procuring a manglar a desired fana' lbase wire having uniform thickness. In practice, I give the wire a hot coat rst, and preferably I have this thin.' In the next step, when the coating is put on by electroplating, the operation can be continued to give exactly a desired thickness. vAt the same 5 time the coating requires a smooth, uniform character which is free from holes, defects, and the like. n

The foregoing `description has been given for clearnessv of understanding only, and no unnecessary limtations are to be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

This application is a division of my co-pending application Serial Number 653,549, led January 25, 1933.

What I regard as new and desire to secure by Letters Patent is: K

l. The process of coating a ferrous article which consists in applying to it by the hot-dip process a coating of cadmium, and electrodepositing thereon an outer coating substantially wholly of cadmium. 4

2. The method of coating a metal to-increase its corrosion resistance comprising `first applying to :it molten cadmium, and then applying a second coating of cadmium @by electropiating over the rst coating.

3..The method of producing a ferrous tirebead reinforcement wire of uniform corrosionresistancc which comprises first coating a ferrous wire with cadmium by the hot-dip process, and` then electroplating cadmium upon the hot-dip wire to produce a uniform coating of desired thickness.

4. A coated ferrous article, comprising a ferrous base having a hot-dipped coating of cadmium thereon, and over that an electrodeposited coating substantially wholly of cadmium.

5. A coated ferrous wire, comprising a ferrous a hot-dipped coating of cadmium thereon, and over that an electrodeposited coating substantially wholly of cadmium.

6. A coated tire bead wire comprisinga ferrous base wire having a hotdipped coating yof cadmium thereon, an electrodeposited `coating substantially wholly of cadmium thereon, and having a coating of rubber vulcanized thereto.

ELGIN CARLETON DOMM. 

